Fix or Dump 8hp Yamaha 2 stroke

[moknots]

Model 8 SD, code 6G1 S, serial 042004 -- was told is was 1990ish.

My brother loaned me this engine (unknown heritage, but definitely used in saltwater) 5 years ago and it ran so well I bought it for $500 to use while I figured out what I really wanted -- a light 2 stroke or a heavy 4 stroke (18' 1962 Glaspar Seafair -- my Avatar). 5 years of fairly heavy use, and not a hicup, until this weekend. Was just getting started trolling (10 minutes?) and apparently failed to notice the telltale had quit flowing -- it slowed then quit, and smelled hot. Would not restart. An hour later it started, but no telltale flow, so I shut it down.

So, do I spend some $ and hours on it, or give up on it? Seems like I could easily get half or more of its value into it just to find out if it will live on or not. I am using my backup (6 hp Mariner, which is a quieter engine), and would be fixing this one to take the role of backup, if it's worth fixing. Advice?

THANK YOU!

[Bloom]

It's easy enough to pull the lower unit and replace the impeller and that may be all it needs. You might want to check the thermostat while you're at it.You should probably do a compression test to rule out a blown gasket. Both parts are cheap enough to make it worthwhile to see if it runs ok after replacing. Definitly worth the small effort and low cost.

You can go on-line for step-by-step instructions, but it's really easy.

[RGB]

I had the same thing happen to my 1998 two stroke 6hp Yamaha about five years ago. My motor seized up while I was warming it up on the way to the mouth of the Lewis. My water pump impeller was shot. I put in a new one, and it's run perfect ever since. I think it cost about thirty five bucks back then. I'm probably due for another one.

[boone]

I have pulled apart 2 longshaft 9.9 Yamaha's, one from 1988 and the other from 1991 and I can tell you that Yamaha had some real issues with corrosion. If they were put together with some type of anti seize you may be ok. Both of the motors had the extra long shaft so they had the 5" extension kit. The bolts were so corroded that they broke off even with lots of PB Blaster and heat to loosen them. Once I had the bolt heads off I figured ok no problem but the bolts were corroded inside the extension. I was able to salvage one of the two. Another issue on the four strokes anyway was that the middle housing would split from salt corrosion due to plugged water passages if they were not properly flushed before storing them. Now all that being said you have nothing to lose by replacing the water pump impeller which is real easy to do if you can get the lower unit to come off easily.

[moknots]

Originally Posted by boone

real easy to do if you can get the lower unit to come off easily.

I suspect that's a big IF. Thanks for the warning. I have signs of saltwater corrosion (white crystaline deposits restricting the telltale and around the seam where the lower unit mates up) and am feelling a little concerned -- thanks for the warning! Mine is a short shaft.

Any hot tips on getting the thing apart? I guess I'll dig out my e-z outs. What's PB blaster? Best heating sequence for enouraging the bolts to let go of the aluminum?

[baitsauce]

I have a 9.9 Merc Bigfoot and changing the impeller will be one of my wintertime projects. It's running fine. I just think it's time. I already picked a new impeller up. I'm just holding off until I put it away for the winter. Cheap insurance.

I think you won't have any problems after you change your's.

Good luck and let us know how it goes.

[baitsauce]

Originally Posted by moknots

I suspect that's a big IF. Thanks for the warning. I have signs of saltwater corrosion (white crystaline deposits restricting the telltale and around the seam where the lower unit mates up) and am feelling a little concerned -- thanks for the warning! Mine is a short shaft.

Any hot tips on getting the thing apart? I guess I'll dig out my e-z outs. What's PB blaster? Best heating sequence for enouraging the bolts to let go of the aluminum?

The only thing I can say is DO NOT RUSH IT. You can try "freeze off" (I think it's called). It comes in an aerosol can. I picked it up at NAPA when I had a similar issue with the heater hose fitting not wanting to let go of the intake manifold.

[boone]

I had no problem getting them out once I was able to get past the extension. They were busted off and I just put a good pair of vise grips on them and spun them right out. My issues came trying to get past the corrosion to start with. PB Blaster is a rust/corrosion eater. On your 2 stroke I would get it off the boat and stand it on it's top (make sure you brace it to keep it upright) since you do not have to worry about oil draining out of it and spray it down good with some kind of rust eater like Break Free, PB Blaster or Corrosion X to break down the rust and or corrosion. Even if you break the bolts you should be able to get them out easy enough. The tough part will probably be getting the lower unit to come free of the center housing. Be real careful of the cavitation plate they break easily.

[Lou]

Like the above have said.
Most likely your impeller, on the water pump.
It's easy, once you get past the tear down.
Take your time and use Breakfree or the like.
Let us know